The objective of the proposed research is to understand host mechanisms involved in suppression of neoplastic disease. We have developed a murine virus leukemia model in which we can suppress established infections using an agent that induces interferon and stimulates an immune response to both virion and virus coded cell membrane leukemic antigens. Our aim is to determine the role of each component of the host response to this oncornavirus infection in the suppression of erythroleukemia. We have found that the virus genome remains in a dormant state for many months after suppression of erythroleukemia. We intend to characterize the dormant virus genome and identify the host responses that maintain the virus genome in such a dormant state. Finally, characterization of the leukemosuppressive factor in statolon will hopefully permit development of effective immunotherapy of neoplastic disease in man.